1. Field of the Invention
The present invention relates to a polarized electromagnetic relay, and more particularly to such a relay with a swingable armature pivotally supported at its center for movement between two contact operating positions.
2. Description of the Prior Art
Polarized electromagnetic relays with a swingable armature pivoted at its center are known, for example, as disclosed in German Patent Publication (Auslegeschrift) No. 2,148,377 and in U.S. Pat. Nos. 4,160,965 and 4,286,244. In such relays, the center-pivoted armature is held on a supporting member by a pair of pivot pins which are rotatably inserted in corresponding bearing holes. This pivotal connection of the armature relies upon the conventional friction coupling and therefore is naturally subject to wearing, which causes a misalignment of the pivot axis of the armature during an extended number of relay operations and therefore reduces accuracy in the swinging movement of the armature, resulting in unreliable contacting operation. Such misalignment becomes increasingly critical for a miniaturized relay which is required to effect the contacting operation only at a limited stroke of the armature movement, and therefore should be eliminated for the fabrication of miniature relays.
Besides, the armature and the movable contact springs are mostly preferred to be combined into a one-piece structure for easy fabrication of the relay, particularly for miniature relays. To this end, it has been a usual practice to carry the movable contact springs on the armature, as taught in the above U.S. Pat. No. 4,286,244. However, the armature is still required to include the pivot pins separately formed from the armature or movable contact springs, which is not sufficient in reducing the number of components associated with the armature, thus failing to provide an efficient design for miniaturization of the relay.